Process of recovering sucrose from cane molasses



Sept. 20, 1932.

A. L. HOLVEN Filed Feb. 6, 192a CANE MOLASSES DILUTE WITH WATER TO Tosouos ADD SUFFICIENT BARIUM HYDRO XIDE TO NEUTRALIZE TO pH 7.0

I HEAT TO APPROXIMATELY BOILING MAINTAIN IN A NEUTRAL CONDITION BY THEADDITION OF FURTHER QUANTITIES OF BARIUM HYDROXIDE IF NECESSARY WHILETEMPERATURE IS BEING MAINTAINED I GRADUALLY ADD TO THE HEATED SOLUTION ASUFFICIENT AMOUNT OF BARIUM HYDROX- IDE TO ELIMINATE. THE DESIREDQUANTITY OF INVERT SUGAR AND OTHER IMPUFIITIES I FILTER TO REMOVE THEPRECIPITED IMPURITIES FILTRATE CONCENTRATE THE F'ILTRATE OF MOLASSESLIQUOR T APPROXIMATELY %0R MORESOLIDS SALTS TO THE REGENERATION SYSTEMRESIDUE SEND THE RESIDUE CONSISTING 0F BAFIIUH ADIJUST TOATEMPERATURE OFFROM APPROXIMATELY To 90C PREPARE. A SOLUTION CONTAINING 20;;

To 30% BARILIM OXIDE IN WATER HEAT TO APPROXIM'ATELY TO C ADD MOLASSESLIQUYDR TO BARIUM HYDROXIDE'. SOLUTION TO PRECIPITATE BARIUM SACCHARATEFILTRATE.

PRECIPITATE WASH WITH BARIUM HYDROXIDE SOLUTION USE THIS WASH WATER FORDILUTING ORIGINAL MOLASSES.

MIX DREOIPITATE OF BARIUM SACCHARATE WITH WATER CARBONATE. WITH CARBONICACID GAS(CO2) UNTIL ALL. BARIUM SACCHARATE HAS BEEN DECOMPOSED CARBONATEWASTE WATER WITH OARBONIC ACID GAS (con TO PRECIPITATE BARIUMAS BARIUM'CARBONATE.

FILTER PRECIPITATE OF BARIUM CARBONATE FILTRATE' ADD SUFFICIENT SOLUBLENON-POISONOUS SULPHATES TO PRECIPITATE THE REMNANT OF SOL- UBLE BARIUMSALTS.

FILTER AND WASH PRECIPITATE WITH WATER TREAT WITH SULPHUR DIOXIDE (50 TOPRECIPITATE REMAINING BARIUM AS BARIUM SULPHITE FILTER PRECIPITATE OFBARIUM SULPHITE FILTRATE PRECIPITATE OF BARIUM FILTRATEL CARBONATE &BARIUM SULPHATE TREAT IN ANY MANNER SUITABLE FOR THE RE- EVAPORATE THEFILTRATE OF SACCHARATE LIQUOR TO RECOVERY OF SUCCOSE.

V COVERY OF POTASH SALTS OR OTHER VALUABLE BY-PRODUGT5 IN VEN TOR.

REGENERATION SYSTEM BY FOR THE PRODUCTION OF 4 rm EITHER BARIUM OXIDE ORTTORNEYS.

BARIUM HYDROXIDE.

Patented Sept. 20, 1932 UNITED STATES- PATENT OFFICE ALFRED L. HOLVEN,OF CROCKETT, CALIFORNIA Application filed February 6, 1928. Serial No.252,078.

This invention relates particularly to the recovery of sucrosefrom canemolasses by means of a process involving the use of barium in the formof either barium oxide or barium hydroxide.

The recovery of sucrose from beet molasses may be readily accomplishedby processes wherein the sucrose is precipitated as either calciumsaccharate or barium saccharate, but when these same processes have beenapplied to cane molasses the recovery of sucrose has not beensufliciently great to justify the operations. The difference in theresults obtained when applying similar desugarization processes to bothbeet and cane molasses may be directly attributed to the fact that canemolasses contains a relatively large proportion of invert sugars, whilethese products are practically absent from beet molasses. Thedifliculties encountered during the attempted application of suchprocesses to cane molasses have been due principally to the fact thatthe invert sugar decomposes to form impurities which have made itimpossible to satisfactorily recover the sucrose therefrom. Theprincipal objects of the present invention are, therefore, to provide amethod of satisfactorily eliminating the in-- v'ert sugar from canemolasses and to subsequently recover the bulk of the sucrose present insaid classes. I

It has b en proposed by Deguide in his German Patent No. 395,563 to addcaustic baryta to the molasses when cold and subsequently heat the massto the boiling point to eliminate reducing sugars. He then adds anadditional amount of caustic baryta to the molasses and again heats itto the boiling point to precipitate the barium saccharate therein; Thepresent invention distinguishes over this disclosure in several veryimportant respects, as a result of which, a greater quantity and asuperior quality of sucrose is recovered. Among the more importantdistinguishing differences are the following:

1. When the caustic baryta is added to the cold solution and during thesubsequent heating, as disclosed by Deguide, barium saccharate will beprecipitated with the reducing sugars and therefore lost, whereas, whenloss of'the latter, as suggested above will-be prevented.

2. Deguide suggests the addition of the entire amount of bariumhydroxide in one step, so Whereas in the present case the barium oxideor hydroxide is not added to the heated molasses all at one time. Thisdifference is material as it has been found to be very important thatthe barium oxide or hydroxide u be gradually supplied to the heated andneutralized molasses in adequate quantities to maintain a sufficientlyalkaline condition to rapidly eliminate reducing sugars, the additionsso made being so regulated that the alkalinity of the solution will bemaintained below a point at which barium saccharate will be formed.

I 3. In the present case the molasses, after the removal of reducingsugars, is added to the barium hydroxide solution where the bariumsaccharate is precipitated in the presence of a desirable excess ofreagent and a high alkalinity with relatively smallamounts ofimpurities. This practice produces a; large grained saccharate of highpurity, whereas it has been found by experiment that when bariumhydroxide is added to the molasses, as disclosed by Deguide, a smallerained saccharate contaminated by undesira le im- 5 purities results.

The present invention contemplates the use of alkaline conditionsproduced by the addition of either barium oxide or barium hydroxide tothe diluted and heated molasses in order to eliminate invert sugars,thereafter again using barium in the form of either barium oxide orbarium hydroxide to precipitate the sucrose in the form of insolublebarium saccharate. It has been found that by properly 05 and carefullycontrolling the temperature and the addition of barium, as hereinafterspecified, in the form of either barium oxide or barium hydroxide,during the steps of this process, it is possible to efficiently recovera greater quantity of the sucrose in a relatively pure form than hasheretofore been possible. This invention is illustrated by way ofexample in the accompanying diagram which shows a flow plan indicatingthe steps of the process.

It has been found in the analysis of cane molasses that the sucrose isusually associated with approximately an equal weight or less of invertsugars. In the recovery ofthe sucrose from such a molasses by thisprocess it is necessary to eliminate a suflicient amount of the invertsugars to make it possible to recover the sucrose in a relatively pureform. This is accomplished in the present invention in the mannerdescribed below.

As a first step in this accomplishment, the molasses is diluted to suchan extent that it contains from 20% to 40% of solids. The only featurewhich necessitates the above dilution of the product is the filtrationof the treated liquor and it will therefore be quite probable that sometypes of molasses may be filtered with a higher percent of solids thanis indicated above. The rate of reducing sugar elimination ispractically independent of the percentage of solids in solution but ithas been found that more economic operation can be maintained where itis practical to maintain a high percentage of solids in solution.Suflicient barium in the form of a solution of barium oxide or bariumhydroxide is then added to neutralize the acids present in the originalmolasses to such an extent that the neutralized molasses has a hydrogenion concentration of approximately pH 7.0.

This condition should be maintained by the addition of such furtherquantities of barium hydroxide or barium oxide as may be necessaryduring the subsequent heating of the neutralized solution. The additionof barium oxide. barium hydroxide, or other alkaline reagent at thisstage of the process is not necessarily an essential step in theoperation of this process, but it results in the recovery of a greaterproportion of the sucrose by preventing the loss of sucrose throughinversion during-the heatingof the molasses which would otherwise becomesufliciently acid to convert a part of the sucrose to invert sugars.

The neutralized solution is then heated to approximately the boilingpoint and thereafter bariumin the form of a solution of eitherbariumoxide or barium hydroxide is gradually added thereto for thepurpose of eliminating invert sugars andother undesirable impurities.The temnerature indicated above is approximate and maybe exceededslightly in this instance as the solution is so dilute that there willbe no destruction of sucrose due to overheating. Variations from thistemperature can be more safely made in the opposite direction and can goas low as 80 C. The invert content need only be reduced to a point whereit will no longer be an interfering factor in subsequent operations. Thetime required in carrying out this operation has been found to beapproximately twenty minutes. The amount of barium oxide or bariumhydroxide may vary with diiferent types of molasses, but a suflicientamount of the above reagent is to be added to render the process asdescribed commercially or economically profitable. The amount of bariumoxide (BaO) required for the elimination of invert sugars will beapproximately equal to the weight of said invert sugars. On some typesof molasses, however, it may be desirable to use somewhat more bariumoxide in order to eliminate other impurities which would'interfere withthe sub sequent recovery of the sucrose.

Attention is particularly-directed to the fact that the barium, in theform of a solution of either barium oxide or barium hydroxide, used forthe elimination of invert sugars. is not mixed with the molasses priorto its di ution or its boiling, but to the boiling solution therebyinsuring that the barium added at this stage will be mixed with themolasses at the optimum temperature for reactions which will tend toeliminate invert sugars but not to produce barium saccharate Attentionis also directed to the fact that in the present process, the barium, inthe form of barium oxide or barium hydroxide, is

gradually supplied to the neutral and heated molasses liquor eithercontinuously or intermittently by the frequent addition of smallportions in such a manner as to maintain the solution in a sufficientlyalkaline condition to eliminate invert sugars, but below the alkalinityat which any appreciable quantity of barium saccharate will be formed.An excessive alkalinity, which would be produced by the addition of anexcess of barium hydroxide or barium oxide, must be avoided,

inasmuch as such an excessive alkalinity would result in a precipitationof barium saccharate, with a consequent decrease in the amount ofsucrose which can be recovered.

After the elimination of the desired amount of invert sugars has beencompleted as a result of the combined influence of heat and alkalineconditions, the treated molasses liquor is then filtered, thus removingfrom the treated molasses liquor the insoluble decomposition productsproduced during the elimination of invert sugars. As the resultingfilter cake of insoluble decomposition products contains barium salts.it is subjected to a process suitable for their regeneration to bariumhydroxide or barium oxide. The filtered molasses liquor is thenconcentrated to a density at which the precipitation of sucrose as abarium saccharate may be most efliciently accomplished. Under mostconditions, a concentration to approximately 80% solids is satisfactoryfor this purpose. Where the viscosity of the molasses is such that itcan be readily agitated, a higher density is preferable, as the recoveryof sucrose therefrom varies in proportion with the percent of solids inthe solution. Under some conditions, however, it may be desirable toconcentrate the treated liquor prior to the removal of the insolubledecomposition products by filtration, rather than after filtration,since an additional amount of impurities which may have been renderedinsoluble during the concentration are thereby also eliminated. Such achange, however, is merely a change in the sequence of the operations ofthis process and is included as a part of the present invention.

The filtered and concentrated liquor is then ready for the second stepof the process,

which consists of a treatment with barium in the form of a solution ofbarium hydroxide, in order to precipitate the sucrose as a bariumsaccharate. It has been found that the weight of barium (as dry bariumoxide, which, in solution, is barium hydroxide) required for apractically complete precipitation of the sucrose from the molassesliquor will be equal to from 60% to 7 0% (expressed as barium oxide,BaO) on the total weight of sucrose present in the molasses liquor. Thefiltered and concentrated molasses liquor is adjusted to a temperatureof approximately 75 C. and is then added to the required amount of asolution containing approximately to 30% of pulverized or finely dividedbarium oxide or an equivalent amount of barium hydroxide, the lattersolution having been heated to approximately 80 C. to 90 C. previous tothe addition of the hot con centrated molasses liquor thereto. Attentionis directed to the fact that the hot concentrated molasses liquor isadded to the barium hydroxide solution, rather than the reverse. Thismethod of procedure insures that at this stage of the process themixture of molasses, liquor and barium hydroxide solution will bemaintained at the exceedingly high alkalinities which represent theoptimum condition of alkalinity for the combination of barium I oxideand sucrose to form barium saccharate.

It has been found in this connection that if a small quantity of bariumsaccharate from charate appear to act as nuclei of crystallization forfurther quantities of barium saccharate, thereby aiding in the formationof a granular precipitate of barium saccharate which can be very readilyfiltered and washed in the subsequent operations of this process. It isalso desirable to'employ a vigorous agitation within the solution duringthe time that the barium saccharate is being formed.

This agitation causes a rapid and intimate I @5 mixing of the bariumhydroxide and the molasses liquor and results in an economy of reagent,a more complete recovery of the sucrose, and the production of a.granular precipitate which can be readily filtered. After theprecipitation of the sucrose in the form of barium saccharate has beencompleted, the solution is again filtered to separate the precipitatedbarium saccharate from the almost completely desugarized liquor. Afterthe filtration, the precipitate of barium saccharate is washed with asolution of barium hydroxide for the purpose of displacing and washingaway the soluble impurities in the barium saccharate precipitate. Theaddition of either barium oxide or barium hydroxide to the wash water isnecessary in order to prevent the solution of any of the barium.saccharate during washing operations. The wash water containing bariumhydroxide may then be added to the waste water, or it can be usedinstead of pure water for diluting the original molasses prior to theelimination of the reducing sugars. This procedure is recommended as thewash water contains more or less sucrose which will then be readilyrecovered in the next sac charate operation. The combined wash and wastewaters, or the waste water as the case may be, is then subjected to theaction of carbonic acid gas until soluble barium salts have beenprecipitated in the form of insoluble barium carbonate. The preci itateof barium carbonate may be removed y filtration and subjected to aprocess suitable for regeneration to either barium hydroxide or bariumoxide. When the reducing sugars are decomposed by barium hydroxide,barium lactate and similar compounds are formed. These are solublecompounds which cause considerable barium to be present in the wastewater, and therefore, for economic operation this barium should beprecipitated and "recovered. These compounds are so stable that bariumcannot be completely precipitated therefrom by carbon dioxide, but ithas been found possible and desirabletoprecipitatethe barium as bariumsulphite by the use of sulphur dioxide gas. The filtrate from thecarbonated wash and waste waters may be treated in many manners suitablefor the recovery of the potassium carbonate or other valuableby-products present therein.

The precipitated barium saccharate is resuspended in water and dispersedby agitation. Carbonic acid gas is then passed through thesolution untilall of the barium saccharate has been decomposed with the liberation ofsucrose and the formation of in soluble barium carbonate. The carbonatedsaccharate liquor is then treated with a suflicient quantity ofsulphates to precipitate any soluble barium salts which have not beenprecipitated in the form of barium carbonate. While any solublenon-poisonous sulphate may be used in the accomplishment of this result,it may often be desirable to precipi tate the remaining soluble bariumsalts by the addition of such sugar solutions as contain appreciablequantities of sulphate salts and have a purity approximately the same asthat of the saccharate liquor. have recommended the use of any solublenon-poisonous sulphate for the precipitation of barium from thesaccharate liquor, it has v been found particularly advantageous to usealuminum sulphate for this purpose, the typical reaction of which is asfollows:

Some of the advantages in using aluminum sulphate are that the barium isprecipitated as insoluble barium sulphate and the aluminum ion issimultaneously precipitated as aluminum hydroxide (thus effectingpurification without increase in melassigenic salts), and the aluminumhydroxide so formed has a very desirable defecating action on thesolution. The carbonated saccharate liquor is then filtered in order toremove from said liquor the precipitated barium carbonate and bariumsulphate. The residue of barium carbonate and barium sulphate is thenreturned to a regenerating system from which either barium oxideorbarium'hydroxide may be recovered. Under conditions where theintroduction of barium sulphate into a system which regenerateseither,barium oxide or barium hydroxide is undesirable, the addition ofsulphates as described above may be made in an independent step afterthe filtration of the carbonated liquor has been completed.

The filtered and carbonated saccharate liquor is now a solutioncontaining so few impurities that sucrose may be readily obtainedtherefrom by the usual processes of crystallization.

It will thus be seen that by the means here shown, a substantiallycontinuous recovery of sucrose may be obtained from cane molasses, andthat practically all of the sucrose present in sagi molasses may beobtained therfrom in a relatively pure form.

While I have described a preferred method of carrying out my invention,it is to be understood that various changes may be made betweenthelimits herein set forth and in the sequence of operations withoutdeparting from the spirit of the invention as defined in the appendedclaims.

Having thus described mv invention, what I claim and desire to securebyLetters Patent 1. A process of cane molasses treatment for therecovery of the sucrose contained therein, which consists in forming adiluted solution of cane molasses, then heating said solution to atemperature between 80 and 110 C. during which time an alkaline earthWhile 1.

metal hydroxide is added to the solution in suflicient quantities tomaintain the solution in a neutral condition, and thereafter addingfurther quantities of the alkaline earth metal hydroxide during thecontinued heating of the solution so as to eliminate invert sugar andother impurities from the solution but insuflicient to precipitate thesucrose and then separating the precipitated impurities from thesolution.

20A method of recovering sucrose from cane molasses, which consists indiluting the molasses with water, thereafter raising the temperature ofthe solution to a temperature between 80 and 110 (1., during which timebarium hydroxide is added in quantities sufficient to establish aneutral condition and to maintain the same, then gradually adding to theheated solution barium hydroxide in an additional amount sufficient tocause the invert sugar and other impurities to be eliminated from thesolution but insufiicient to precipitate the sucrose, thereafterseparating the solution fromthe-precipitateby filtration, thenconcentrating said filtrate to approximately 80% solids, then addingsaid concentrated filtrate to a barium hydroxide solution so as toprecipitate the sucrose in the form of barium saccharate, and thenfiltering the barium saccharate from the solution.

3. A method of recovering sucrose from cane molasses, which consists indiluting the molasses with water, thereafter raising the temperature ofthe solution to a temperature between 80 and 110 0., during which timebarium hydroxide is added in quantities sufficient to establish aneutral condition of the solution and to maintain the same, thengradually adding to the heated solution barium hydroxide in anadditional amount suf- 105 ficient to cause the invert sugar and otherimpurities to be eliminated from the solution but insuflicient toprecipitate the sucrose, thereafter separating the solution from theprecipitated impurities by filtration, then concentrating said filtrate,then adding said concentrated filtrate to a solution of barium hydroxidewhereby barium saccharate will be formed, then filtering the bariumsaccharate from the solution, then treating the barium saccharate insuch a manner as to liberate the sucrose therefrom and to precipitatethe barium, and then filtering the solution.

4. A process of treating molasses substantially free from invert sugarto recover the sucrose therefrom, one step of which consists in, addingto the sugar liquor derived by carbonation of the barium saccharate,aluminum sulphate in order to precipitate barium salts present asimpurities in said sugar liquor.

5. A process of cane molasses treatment for the recovery of the sucrosecontained therein, which consists in forming a solution of canemolasses, then heating said solution to a temperature between 80 and 110C. during which time an alkaline earth metal hydroxide is added to thesolution in sufl ficient quantities to maintain the solution in aneutral condition, and thereafter but prior to the precipitation ofsucrose adding further quantities of the alkaline earth metal hydroxideduring the continued heating of 10 the solution in suflicient quantitiesto eliminate only the invert sugar and other impurities from thesolution, then separating the recipitated impurities from the solutionby tration, and finally precipitating the su- 15 crose as a saccharateby the addition of an earth metal hydroxide.

6. A method of recovering sucrose from cane molasses, which consists indiluting the molasses with water, thereafter raising the :0 temperatureof the solution to a temperature between 80 and 110 C. during which timebarium hydroxide is added in quantities suflicient to establish aneutral conditon and to maintain the same, then gradually :5 adding tothe heated solution barium hydroxide in an additional amount suflicientto cause the invert sugar and other impurities to beeliminated from thesolution but insufficient to precipitate the sucrose, thereafter 3oseparatin the solution from the precipitate by filtration, then addingsaid filtrate to a barium hydroxide solution so as to precipitate thesucrose in the form of barium saccharate, and then filtering the ba'riumsac- ."35 charate from the solution.

ALFRED L. HOLVEN.

